Condensed consolidating financial information - Condensed consolidated income statement (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 29, 2017	Apr. 30, 2016
Condensed Income Statements, Captions [Line Items]
Sales	$ 1,403.4	$ 1,578.9
Cost of sales	(912.2)	(978.5)
Gross margin	491.2	600.4
Selling, general and administrative expenses	(452.8)	(462.7)
Other operating income, net	76.9	74.3
Operating income	115.3	212.0
Intra-entity interest income (expense)	0.0	0.0
Interest expense, net	(12.6)	(11.8)
Income before income taxes	102.7	200.2
Income taxes	(24.2)	(53.4)
Equity in income of subsidiaries	0.0	0.0
Net income	78.5	146.8
Dividends on redeemable convertible preferred shares	(8.2)	0.0
Net income attributable to common shareholders	70.3	146.8
Consolidation, Eliminations
Condensed Income Statements, Captions [Line Items]
Sales	0.0	0.0
Cost of sales	0.0	0.0
Gross margin	0.0	0.0
Selling, general and administrative expenses	0.0	0.0
Other operating income, net	0.0	0.0
Operating income	0.0	0.0
Intra-entity interest income (expense)	0.0	0.0
Interest expense, net	0.0	0.0
Income before income taxes	0.0	0.0
Income taxes	0.0	0.0
Equity in income of subsidiaries	(109.7)	(316.4)
Net income	(109.7)	(316.4)
Dividends on redeemable convertible preferred shares	0.0
Net income attributable to common shareholders	(109.7)	(316.4)
Signet Jewelers Limited | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	0.0	0.0
Cost of sales	0.0	0.0
Gross margin	0.0	0.0
Selling, general and administrative expenses	(0.2)	(0.1)
Other operating income, net	0.0	0.0
Operating income	(0.2)	(0.1)
Intra-entity interest income (expense)	0.0	0.0
Interest expense, net	0.0	0.0
Income before income taxes	(0.2)	(0.1)
Income taxes	0.0	0.0
Equity in income of subsidiaries	78.7	146.9
Net income	78.5	146.8
Dividends on redeemable convertible preferred shares	(8.2)
Net income attributable to common shareholders	70.3	146.8
Signet UK Finance plc | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	0.0	0.0
Cost of sales	0.0	0.0
Gross margin	0.0	0.0
Selling, general and administrative expenses	0.0	0.0
Other operating income, net	0.0	0.0
Operating income	0.0	0.0
Intra-entity interest income (expense)	4.7	4.7
Interest expense, net	(4.9)	(4.9)
Income before income taxes	(0.2)	(0.2)
Income taxes	0.0	0.0
Equity in income of subsidiaries	0.0	0.0
Net income	(0.2)	(0.2)
Dividends on redeemable convertible preferred shares	0.0
Net income attributable to common shareholders	(0.2)	(0.2)
Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	1,325.2	1,518.3
Cost of sales	(895.4)	(969.1)
Gross margin	429.8	549.2
Selling, general and administrative expenses	(421.5)	(438.6)
Other operating income, net	77.2	71.6
Operating income	85.5	182.2
Intra-entity interest income (expense)	(45.4)	(46.9)
Interest expense, net	(4.1)	(3.7)
Income before income taxes	36.0	131.6
Income taxes	(15.4)	(54.2)
Equity in income of subsidiaries	8.7	85.2
Net income	29.3	162.6
Dividends on redeemable convertible preferred shares	0.0
Net income attributable to common shareholders	29.3	162.6
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Sales	78.2	60.6
Cost of sales	(16.8)	(9.4)
Gross margin	61.4	51.2
Selling, general and administrative expenses	(31.1)	(24.0)
Other operating income, net	(0.3)	2.7
Operating income	30.0	29.9
Intra-entity interest income (expense)	40.7	42.2
Interest expense, net	(3.6)	(3.2)
Income before income taxes	67.1	68.9
Income taxes	(8.8)	0.8
Equity in income of subsidiaries	22.3	84.3
Net income	80.6	154.0
Dividends on redeemable convertible preferred shares	0.0
Net income attributable to common shareholders	$ 80.6	$ 154.0